Mechanical hammer



Aug. 16, 1938. B. w. sNoDGRAss MECHANICAL HAMMER Filed Dec. 4, 1934 4 Sheets-Sheet l w a O n U 5 4 WW 5 Aug. l6, 1938. B. w. SNODGRASS MECHANICAL HAMMER Filed Dec. 4, 1934 4 Sheets-Sheet 3 Aug. 16, 1938. B. w. SNODGRASS MECHANICAL HAMMER Filed Dec. 4, 1934 4 Sheets-Sheet 4 m w 1W5? m I m% 7 m mm M F R Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to mechanical hammers, and more particularly to mechanical hammers of portable type adapted to operate tool elements such as drills, chisels, formers, hammers, and the like, and has as an object to provide an improved arrangement and assembly of elements effective to operate such tool elements in a practical and efiicient manner.

A further object of the invention is to provide improved means for actuating a reciprocating impact element in a mechanical hammer.

A further object of the invention is to provide improved means for operatively interconnecting rotary power means and a reciprocable impact element in a mechanical hammer.

A further object of the invention is to provide an improved arrangement and assembly of elements for operatively mounting a reciprocable impact element in a mechanical hammer.

A further object of the invention is to provide improved means automatically operable by the impact element actuating means to rotate the shank of a tool cooperating with a mechanical hammer.

A further object of the invention is to provide improved means automatically operable by the impact element actuating means to feed a tool and mechanical hammer assembly toward the work to be performed.

A further object of the invention is to provide an improved mechanical hammer susceptible of practical development in a variety of specific forms, readily adaptable to a wide variety of specific uses, positive and eflicient in operation, relatively simple and inexpensive of manufacture, and requiring a minimum of maintenance in use.

My invention consists in the construction, arrangement and combination of elements hereinafter set forth, pointed out in my claims and illustrated by the accompanying drawings, in which- Figure 1 is a longitudinal section axially of a hammer assembly embodying the principles of the invention. Figure 2 is a cross section, on an enlarged scale, taken on the indicated line 2-2 of Figure 1. Figure 3 is a cross section, on the same scale as Figure 2, taken on the indicated line 3--3 of Figure 1. Figure 4 is a fragmentary detail section of and at right angles to the showing of Figure 3. Figure '5 is a fragmentary detail section, on the same scale as Figure 2, taken axially of an air piston employed in the assembly according to Figure 1. Figure 6 is a longitudinal 55 section axially of an improved hammer assembly modified somewhat in respect of the showing of Figure 1. Figure '7 is a cross section, on a scale enlarged relative to Figure 6, taken on the indicated line 'I-1 of the latter figure. Figure 8 is a cross section, on the same scale as Figure '7,

taken on the indicated line 8-8 of Figure 6. Figure 9 is a fragmentary detail section, on a further enlarged scale, illustrating certain details of the showing of Figure 8. Figure 10 is a longitudinal section axially of an improved hamsembly yet further modified in respect of the showing of Figure 1. Figure is a detail cross section taken on the indicated line l5l 5 of Figure 14.

In the construction of the improved" hammer as illustrated in Figures 1 to 5, inclusive, the numeral designates a suitable frame member, preferably formed as ahollow cylinder, arranged to support and house the operative elements of the assembly. One end of the member 20 is closed, as by means of a removable plate 2|, and suitable means, such as a T-handle 22, is provided adjacent the closed end of the member 20 whereby the assembly may be conveniently manipulated. Positioned in' axial alinement within and adjacent the closed end of the member 20, an armature 23 of an electric motor assembly is mounted for rotation in suitable bearings carried by said member 20, the complementary magnetic poles or fields of the motor assembly being indicated at 24 surrounding the armature 23 in fixed relation within the member 20 to complete a power unit carried by and housed within said member, alined with the armature 23, a relatively long, tubular impact element 25 is positioned axially within the member 20 and fiotatively mounted for free rotation and reciprocation relative to said member in suitable spaced anti-friction bearings 26 carried by said member. The end of the element 25 adjacent the armature 23 is closed save for a splined central aperture arranged to slidingly receive a splined portion of the extended armature shaft 23', thus engaging the element 25 and armature 23 for simultaneous rotation and feathering the former to the latter for relative axial reciprocation therebetween, the opposite end of the element 25 being closed by means of a preferably replaceable impact head 21. To utilize rotation imparted to the element 25 by the armature 23 to effect reciprocation of said element, an annular race or track 28 is fixed to the member between the bearings 26 in surrounding relation with the element 25, said race 28 being provided with a plurality of uniformlyspaced cam bosses 29 projecting from that race surface most nearly adjacent the motor assembly and arranged to cooperate with a freely rotatable cam follower 30 carried exteriorly of the element on a stud or spindle fixed to and projecting radially from said element, so that, as the element 25 is caused to rotate, the cam follower is caused to traverse the race 28 and ride over the cams 29 thereof, each said cam imparting axial displacement to the said element 25 in the direction of the motor assembly. Travel of the element 25 in the direction of the motor assembly is limited and reverse travel of said element initiated by a resiliently yieldable member, illustrated in this instance as a frusto-conical sheet spring 3|, fixed within the member 20 adjacent the race 28 in surrounding relation with the element 25 and in the path of an annular flange 32 fixedly carried by said element 25, the resiliently yieldable member being arranged for compression toward and expansion away from the motor assembly, so that motion of the element 25 toward the motor assembly results in engagement of the flange 32 with the resilient member 3|, compression of the latter, limitation of the travel of the moving element in the one direction and initiation of travel of said element in the opposite direction through recovery of the resilient member, thus establishing a complete cycle of reciprocation for the said element 25. The tool element to be acted upon by the impact element 25 is illustrated as a drill shank 33 loosely mounted in axial alinement with the said element 25 through a bore formed for that purpose in the terminal extension 20 of the member 20, said shank 33 being provided with an annular stop flange 33' arranged to limit extension of said shank within the portion 20 and adapted to be engaged at times by a retaining fork 34 hinged to the portion 20 in position to embrace the shank 33 and prevent accidental unseating of the latter. Within the portion 26 of the frame and positioned adjacent the normally-located inner shank end, a second resilient element in the form of a frusto-conical sheet spring 35 is arranged in the path of the impact head 2'! and in surrounding relation with the shank 33 to receive and absorb impact of said head when said shank is dismounted or whenever overtravel of the impact element might result from any cause. When the hammer assembly is to be employed in drilling operations, it is desirable that means be provided operable to jet air through and to the working face of the drill tool, such means being illustrated as comprising a piston 36 closely fitted within and freely reciprocable axially of the hollow impact element 25, said element being provided with an air inlet 31 adjacent its non-impact end and said piston being provided with suitable air passages 38 controlled by a check valve 39 arranged to utilize the inertia effect of said piston during reciprocation of the impact element to jet air through a bore in the impact head 21 registering with a longitudinal bore of the drill tool upon impact engagement of said head with said tool.

In the modified construction of the improvement as illustrated in Figures 6 to 9, inclusive, the operating elements are substantially the same in function and interrelation as previously set forth and are modified only in respect of certain additions and equivalent substitutions. In the modified construction, the frame member 20 and motor elements 23 and 24 are the equivalents of and may be identical with those aboverdescribed, but the handle 22 is omitted and the member 20 slidingly mounted on and arranged for travel along a fixed feed frame 40, which latter is swiveled, as at 4 I, to a suitable tripod or other mount, as is common practice. The frame 40 includes a longitudinally disposed, fixed lead screw 42 engaged by an internally-threaded pinion 43 carried by the frame member 20 concentrically with andfor travel along said screw 42, said pinion 43 meshing with a gear 44 fixed to the armature shaft 23' for rotation therewith within the member 28, to the end that rotation of the armature 23 shall act through the gear 44 and pinion 43 to move the latter along the screw 42 and thereby advance the member 20, with its included elements, alongthe frame 40. The impact element 25, mounting bearings 26 and head 2'! of the modification are substantially, and might well be actually, identical with those above described, but in the modification the element 25 is spaced somewhat from the armature shaft 23 and is connected to the latter for rotation therewith by means of an axial stem 45 fixed to said element 25 and terminating in a splined or angular head 46 slidingly received within a complementary bore formed in the said shaft 23. The race 28, cams 29 and follower 30 of the modification correspond closely with those elements as first described and cooperate to the same end, but the resilient element of the modification is illustrated as an expansive coil spring 41 surrounding the chuck 48 is rotatably carried in the impact end I of the member 20, said chuck being arranged to loosely receive the tool shank 33 and being provided with radial notches wherein radial webs 49 formed on the tool shank 33 are engaged to rotatably interconnect the chuck and tool shank. As one means of automatically rotating the chuck 48, spirally inclined segmental surfaces 50 are shown formed on an inner face of the chuck body, which faces are adapted to be engaged at the end of an impact stroke of the element 25 by the ends of pins 5| carried in axial parallelism by and extending from the impact head 21.

In the modification according to Figures 10 to 13, inclusive, is illustrated an improved hammer assembly particularly adapted for use in stoping operations common to mining. As shown in Figure 10, this modification employs an impact element 25 provided with the annular flange 32 mounted for actuation within the frame 20 in the manner shown in Figure 1 and-hereabove described. In place of the resilient element 3| of Figure 1, an expansive coil spring 41' similar to the element 41 of Figure 6 is employed in the manner and forthe purpose described for the element 3|, the track 28-, earns 29 and follower 30 being included to function as hereabove set forth, and the non-impact end of the element 25 is splined to one end of an extended armature shaft 23' for rotation therewith and travel axially thereof. The tool shank 33 is mounted in and extends loosely through a chuck 52 rotatably carried in and adjacent the impact end of the member 20, said chuck being formed with or having secured thereto a star wheel 53 with which a radial lug or finger 54 fixed to a shaft 55 rotatably disposed longitudinally of the member 20 is adapted to cooperate in such manner as to advance the star Wheel one point for each revolution of the shaft 55, thus intermittently rotating the chuck 52 and tool element carried thereby. To rotate the shaft 55, a friction cone 56 is splined to the armature shaft 23' between the motor assembly and element 25 and is yieldingly positioned axially of said shaft 23' by means of an expansive coil spring 51 engaging between said cone 56 and an annular rib fixed to said shaft 23', and a complementary friction cone B is splined to the shaft 55 and yieldingly positioned thereon by means of an expansive coil spring 59 engaging between said latter cone and an annular flange 60 fixed to the shaft 55, so that, as the element 25 approaches the impact end of its stroke, the friction surfaces of the cones 56 and 5B are brought into engagement to transmit rotation of the former to effect rotation of the latter and consequently of the shaft 55, the yieldable positioning of the said cones permitting disengagement of and slipping between their friction surfaces whenever resistance to rotation of the chuck 52 is encountered. To advance the hammer assembly in the direction of drilling operations, a tubular sleeve 6! is mounted for rotation and held against axial displacement in and axially of a conical extension 62 of the member 20 secured to and projecting axially from the motor end of said member. The sleeve 6! is provided with a star wheel 63 secured to its inner end and an. internally-threaded portion adjacent its outer end, and a threaded stem 64 threadedly engages within said sleeve and is formed with a bearing point 64' feathered through and projecting beyond the outer end of the extension 52, so that rotation of the sleeve 6! in one direction acts, through its threaded engagement therewith, to axially extend the bearing point 64 through the frame extension 62 and consequently urge the hammer assembly away from the bearing engaged by the point 64. To rotate the sleeve 6|, the shaft 55 is extended past the motor assembly and provided with a second radial finger or lug 65 positioned in operative relation with the star wheel 63 and arranged to act through the friction drive of the cones 55 and 58, above described, to intermittently advance said star wheel 63 and rotate the sleeve 6|.

In the modified construction illustrated in Figures 14 and 15, rotation of the armature 23 is transmitted through suitable bevel gears 66 and 51 to effect rotation of a shaft 68 disposed transversely of the member 20 adjacent the motor assembly, said shaft being provided with a plurality of cam lobes 69 disposed in a common plane radially thereof and arranged to operatively engage a cam follower l0 rotatably carried on the end of a stem H extending in fixed relation from the impact element 25 through a fixed guide 12 carried by the member 20, so that rotation of the shaft 68 acts through the lobes 69, follower l0 with the rotatable chuck 52, star wheel 53, radial finger 54 and shaft 55 illustrated in Figure and hereabove described, said shaft 55 in this instance being provided with a terminal friction cone 13 'yieldingly held by means of an expansive coil spring M in driven relation with a friction cone 75 mounted on and for rotation with the shaft 58. An impact block is mounted for limited axial motion in the member 28 adjacent the .chuck 52 and is arranged to bear against the inner end of the tool shank 33 and transmit to said tool shank impact received from the element 25, said block 15 being formed with a peripheral channel communicating through radial bores 1'! with a central port 18 adapted to register with the air bore of the tool shank, so that air supplied to the peripheral channel of the said block may be led to and for discharge through the said air bore of the tool shank. To supply air to the peripheral channel of said block, an air pump in the form of an impeller 19 secured to the shaft 68 within a chamber carried within the member is arranged to draw air through suitable ports 80 formed in the member 20 and discharge said air, under pressure, through a conduit 8| connecting said'chamber with the peripheral channel of the said block 16.

It will be noted that all of the constructions illustrated and described provide mechanical means for converting rotary motion of an integral power unit to effect reciprocation of an im pact element, said reciprocation being generated and maintained by power actuation of the impact element in the .direction of and against a resilient element for reaction therefrom, free of mechanical restraints, to Work effect on a relatively fixed, elastic element, and consequent reaction after work effect in the direction of repeated power acceleration, the various specific embodiments of the invention illustrated being all effective to the same end and each presenting a practical and operable construction for a complete, portable, powered, mechanical hammer unit that is highly efficient in operation and adaptable to a wide variety of uses in the field. Since the various mechanical refinements and adjuncts of the improved hammer illustrated and described in connection with specific embodiments of the invention may be employed with and applied to other embodiments of the said invention, and since modification of and variation in the specific form, construction and arrangement of the elements shown and described may be had Without departing from the spirit and essence of the said invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

1. In a mechanical hammer, a casing having front and rear sections, a power unit mounted in the rear portion of the rear section, a rotatable chuck at the front end of the front section, a tool having a bored shank extending through said chuck into the front section and having an impact block at its rear end formed with air passages leading from the bore of the tool shank, an impact member freely slidable longitudinally in the front section towards and away from the impact block and having a stem extending into the rear section and provided with a follower at its rear end, a spring in the rear end of the front section about said stem spaced from the rear end of the impact member for the major portion of movement of the impact member and engageable by the rear end of said impact member to check rearward movement of the impact member and impart rebound thereto, a driven shaft rotatably mounted in the rear section transversely thereof, a spiral cam carried by said shaft for engaging said follower to'shift the impact member rearwardly during rotation of the shaft, a fan housing in the rear section, a fan in said housing carried by said driven shaft, an air conduit leading from said housing to the forward end portion of said front section for delivering air to the air passages of said impact block, means for imparting rotation to said shaft from said power unit, and means for transmitting rotary motion from the driven shaft to the chuck.

2. In a mechanical hammer, a casing having front and rear sections, a power unit mounted in the rear portion of the rear section, a rotatable chuck at the front end of the front section, a tool having a bored shank extending through said chuck into the front section and having an impact block at its rear end formed with air passages leading from the bore of the tool shank, an impact member freely slidable longitudinally in the front section towards and away from the impact block and having a stem extending into the rear section and provided with a follower at its rear end, a spring in the rear end of the front section about said stem spaced from the rear end of the impact member for the major portion of movement of the impact member and engageable by the rear end of said impact member to check rearward movement of the impact member and impart rebound thereto, a driven shaft rotatably mounted in the rear section transversely thereof, a spiral cam carried by said shaft for engaging said follower to shift the impact member rearwardly during rotation of the shaft, a fan housing in the rear section, a fan in said housing carried by said driven shaft, an air conduit leading from said housing to the forward end portion of said front section for delivering air to the air passages of said impact block, a friction disk carried by said driven shaft, a friction disk carried by said power unit and engaging the friction disk of said shaft for imparting rotation to the shaft from the power unit, a transmission shaft extending longitudinally through the front section and into the rear section, means for transmitting rotation from the friction disk of said driven shaft to said transmission shaft, and means for intermittently transmitting rotation from said transmission shaft to said chuck.

3. In a mechanical hammer, a casing having front and rear sections, a power unit mounted in the rear portion of the rear section, a rotatable chuck at the front end of the front section, a tool having a bored-shank extending through said chuck into the front section and having an impact block at its rear end formed with air passages leading from the bore of the tool shank, an impact member freely slidable longitudinally in the front section towards and away from the impact block and having a stem'extending into the rear section and provided with a follower at its rear end, resilient means in the rear end of the front section spaced from the rear end of the impact member for the major portion of travel thereof and engageable by the impact member to check rearward movement of said impact member and impart rebound thereto, a driven shaft rotatably mounted in said rear section driven from said power unit and carrying a cam member for engaging the follower and shifting the impact member rearwardly, a source of air under pressure in said rear section actuated by said driven shaft, an air conduit leading from the source of air under pressure to the front end of said front section for delivering air to the air passages of the impact block, and means for imparting rotation to the chuck.

4. In a mechanical hammer, a casing, a power unit in the rear portion of said casing, a chuck at the front end of said casing, a tool having a shank extending through said chuck into the easing, an impact member freely slidable longitudinally in said casing towards and away from the rear end of the tool shank, a stem for said impact member extending rearwardly in said casing, a cup mounted in said casing about said stem, a spring in said cup spaced from the rear end of said impact member for the major portion of movement of the impact member and engageable by the rear end of the impact member to check rearward movement of the impact member and impart rebound thereto, a driven shaft rotatably mounted in said casing and rotated from said power unit, a cam carried by said shaft, and a follower carried by said stem for engaging said cam whereby reciprocating motion will be imparted to said impact member during rotation of said driven shaft.

BENJAMIN W. SNODGRASS. 

